Enbridge Inc imposed mid-month apportionment on two additional crude oil pipelines between Alberta and the U.S. Midwest on Thursday, two trading sources said.

Space on Line 4, which can carry up to 796,000 barrels per day of heavy crude between Edmonton, Alberta, and Superior, Wisconsin, was rationed by 10 percent, meaning shippers can only move 90 percent of their nominated volumes.

Line 4 was shut down for two days this week after a power outage and only resumed operations on Thursday morning.

The 450,000 bpd Line 67 between Hardisty, Alberta, and Superior, Wisconsin, was also apportioned by 10 percent.

Last month Enbridge said lines 5, 6A and 6B would be apportioned in May.